1. Field of the Invention
The present invention relates to the transmission of electromagnetic energy. In particular, it relates to radiating antennas of cavity design.
2. Description of the Prior Art
Previous design art for thin, electrically small antennas has included the use of active elements (transitors) and dielectric or ferrite materials. Active devices require an external source of energy and are susceptible to environmental changes, such as temperature. Dielectric or ferrite materials tend to decrease radiation efficiency.
The theoretical normal gain and efficiency limitations of electrically small antennas have been defined by Harrington in Time Harmonic Fields (McGraw Hill, 1961). D. Rhodes in the IEEE Transactions on Antennas and Propagation, May, 1972, pages 318-325, has theoretically defined the limitations of frequency bandwidth.
The present invention achieves the maximum limits of gain and bandwidth as theoretically derived above by providing an electrically small rectangular cavity having a T-guide therein.